State Transition and Validation

With the ChainState struct built, the foundation for running a node, we can now dive into the methods that validate and apply state transitions.

ChainState has 4 impl blocks (all located in pruned_utreexo/chain_state.rs):

• The BlockchainInterface trait implementation
• The UpdatableChainstate trait implementation
• The implementation of other methods and associated functions like ChainState::new
• The conversion from ChainStateBuilder (builder type located in pruned_utreexo/chain_state_builder.rs) to ChainState

The entry point to the state transition and validation logic are the accept_header and connect_block methods from UpdatableChainstate. As we have explained previously, the first step in the IBD is accepting headers, so we will start with that.